Manufacture of fuel briquettes



Patented Nov. 10, 1925.

UNITED STATES PATENT OFFICE.

MANUFACTURE OF FUEL BRIQUETTES.

No Drawing.

To all whom it may concern:

Be it known that I, THoMAs AUeUsrUs GosKAR, a subject of the King of Great Britain, residing at Digwood, Esplanade, Burnham-on-Sea, in the county of Somerset, England, have invented certain new and useful Improvements in or Relating to the Manufacture of Fuel Briquettes (for which I have filed application in England, Jan uary 9, 19241, No. 231,934), of which the following is a specification.

This invention relates to a process for the manufacture of fuel briquettes or so-called patent fuel.

A process of making briquettes has been previously proposed in British patent specification No. 120585 which consists in taking raw coal containing from 11 to 17% volatile matter, or mixture of two or more raw coals, containing in the mixture from 11% to 17% volatile matter; or mixtures of raw coal or coals with hydrocarbon binder or coke or both, in which the total volatile matter ranges from 11% to 17%, forming the coal or coal mixture into a mash (for example, by the addition of water) then forming the mash into briquettes; and then subjecting said briquettes to a heat treatment at a temperature of from 1400 F. to 2000 F. (preferably about 1850 F.) in a suitable oven or retort until there is distilled from said briquettes a substantial portion of the volatile contents of the solid matter therein.

and a marked shrinkage takes place; and I neither use nor claim such proposed process.

In British patent specification No. 221526 there is described a process of preparing coal for carbonizing in the manufacture of solid fuel from mixtures of finely divided noncaking coal and caking coal in which the caking coal is ground or pulverized to pass through a mesh of one-sixteenth of an inch or less and such finely divided or pulverized caking coal is formed into an emulsion with water, soft soap and water, creosote or other liquid, and this emulsion is mixed with the non-caking coal which has been previously reduced (e. g. by grinding) to pass through a mesh of one-eighth of an inch or less; and the mixture thus produced is then consolidated by ramming or otherwise compressing such mixture in a mould or trough and apparently While still in said mould or trough, is charged into an oven or retort where the Application filed June 26, 1925. Serial No. 39,747.

mixture is carbonized at a temperature of from 600 to 1200 centigrade; and I neither use nor claim this proposed process.

My present invention differs essentially from both the aforesaid processes in the following respects (inter alia) I (1) The caking coal (in carrying out my invention) is ground or reduced to a very much finer powder or state than 16 mesh 'Or thereabouts namely the caking coal is reduced to an impalpable powder or to such a finely comminuted state as to pass 150 to 200 mesh, or even finer, for forming the binding medium.

(2) I do not form my binding medium as an emulsion; but on the contrary I mix such impalpable powder or finely comminuted caking coal with only sufiicient water or/and tar or other suitable liquid hydrocarbons as to form a smooth homogeneous paste.

(3) After pressing or moulding the final mixture into blocks or briquettes I subject the latter to heat treatment only after removal from the press or mould.

(4) I do not carbonize the final mixture at a temperature of from 600 to 1200 degrees centigrade; but on the contrary the temperatures I employ during the heat treatment range only from about 600 to 1200 F.

The process forthe manufacture of fuel briquettes according to the present invention consists in forming a binding medium from caking coal reduced to an impalpable powder or finely comminuted state such as to pass enough water or/and tar or other suitable liquid hydrocarbons to thereby form a smooth homogeneous paste, mixing a suitable proportion of this binding medium with a base material or materials of a non-caking character such as anthracite or dry steam coal or coke breeze e. g. in the proportions of 30%10% of binding medium to 70%- 90% of the base material or materials, press ing or moulding this mixture into briquettes, removing the latter from the press or moulds and then subjecting the briquettes after removal from the oress or mould to heat treatment as hereinafter described.

In carrying out my present invention I prefer to use as the non-caking coal base,

anthracite, duif, coke breeze, or the like with a volatile content of from 7% to 11%; or to have the combined volatile of my non-caking 150-200 (or finer) mesh mixed with only base and a finely ground caking coal (which, mixed with a suitable liquid forms my binder) of from 7 to 11%.

In this case theprocess consists in mixing the base of non-eaking coal. duff, coke breeze or the like with a binder comprising a powdered or finely comminuted caking coal and a liquid such as coal tar and/or water, the combined volatile content of the non-caking and caking coals being in the region of 77; to 11% pressing the mixture into briquettes and submitting the briquettes'to partial distillation or baking, advantageously at -a temperature of from 600 to 1200 'F. to drive off a proportion of the volatiles, and consolidate the briquette.

Thus 1 start with a volatile content of from 7 to 117- which is considerably lower than the initial volatile :content of prior briquette making proposals, and my final product preferably contains volatiles in the neighbourhood of 5%.

The final product of my present invention is a hard dense and substantially non-porous briquette.

In carrying this invention into effect I reduce the binding coal or coals to a fine powder in any convenientgrinding machine, for instance a tube mill, or I may use =equally fine coal or slurry which has been separated from the main bulk by screening, washing, airblast or water flotation. I then arrange for this fine coal to be converted into a more or less adhesive paste similar to clay by the addition of liquid hydrocarbons, preferably coal tar, and/or water in-any desired proportion. This paste may be made by mixing or pugging it before it is added to the base materials, or the'liqruid or liquids, and powdered or "finely commmuted coal may be addedsimultaneously or in sequence to the base materials, and

mixed together in such a manner that the binding coals and liquids virtually become an adhesive paste as previously. referred to,

between the articles of the non-cakin: coal or I may select coal or coals containing sufficient finely pulverized particles .in its composition.

The component materials are preferably used in the following general proportions by weight viz:

-90% of the base materials to 301O% of the binden The following is'one example of the proportions by Weight of'materials which may be employed in carrying my invention =into practice Percent. Powdered caking coal 15 Water 3 Tar v5 Base material '77 'Theproportioning or measurement ofthe ingredients may be carrled out in any of ,worms geared together and working in an open trough.

When 1t is found necessary to increase the temperature of the mixture above the normal atmospheric temperature, this may be carried out by any of the usual means adopted in coal briquette manufacture, but preferably by the application of steam either direct to the mixture or by steam-jacketing the mixing trough. The mixed base -mate rials and the connninuted binding :coal and water and/or tar then conveyed into -a press of any ordinary design, but preferably into a press generally known as an ovoid making machine. At thispoint of the process the mixture is formed into briquettes which maintain their shape as the result'of the joint action of the mechanical pressure and the adhesive property of the ca'king coal paste .and whichafter removal from the press or mould are strong enough to stand the mechanical handling between the press and the oven or retort as well as to maintain their shape while undergoing the heat treatment.

For the heat treatment the briquettes are conveyed to a retort or'retorts by means of belts, elevators, or other well-known means. The retorts may be of any of the ordinary well-known coal carbonizing types but I prefer to adopt retorts designedtogive a continuous discharge, and toreceive a con tinuous feed, and in particular would select a retort designed to work on the following principles.

The long axis of the retort shoul'dbe vertical or inclined in order that the ovoids might flow through it by gravitation. At the feeding :end, valve or valves are fitted and controlled by the operator to feed the prepared ovoids as andwhen required, and to allow only a minimum loss of gas therefrom.

The retort maybe smaller in cross-section at the feed end than at the discharge end, in order to facilitate the flow of the ovoids towards the I discharge.

The disclra'rgeend of the retort 'mayor may not bewater jacketed in order to cool the finished product to a safe temperature before it emerges to the atmosphere.

The discharge may be of any Ofthe usual designs for such continuous vertical retorts.

In operationproducer gas or highly superheatedinert gas or steam is convevedto tuyeres fitted to the lower'end of the retort and above the water-cooldsection.

The producer gas or superheated "gas and/or steam is maintained at as high a telnperature as practicable, and without the ad dition of air is forced or induced through the tuyeres, and into the interstices or spaces between the briquettes which are in the retort, where it parts with a considerable proportion of its sensible heat to the briquettes, and assists in the partial. distillation or baking.

Steam may or may not be collected and conveyed from the upper part of the retortor steam from another source or water may be forced into the interstices or spaces be tween the briquettes at a level above the discharge device, for the purpose of cooling the r briquettes, and of converting some of the steam into producer gas, as it ascends towards the hot zone of the retort.

The inert gases in their passage between the briquettes are joined by the volatile matter extracted. from the briquettes by the heat, and the mixed gases pass through discharge pipes fitted in the upper part of the retort, and after passing through suitable condensers to extract the moisture and heavier volatile matters, are burnt to provide heat to superheat the inert gases and/or to maintain the walls of theretort at a sufiiciently high tempe 'ature.

hat I claim is 1. A process "for the manufacture of fuel briquettes which consists in :torming a binding medium -from caking coal reduced to an impalpable powder or a finely comminuted state such as to pass 150-200 (or finer) mesh, mixed with only enough liquid such for example as water or/and tar or other suitable liquid hydrocarbons to thereby form a smooth homogeneous paste, mixing a suitable proportion of this binding medium with a base material or materials of a noncaking character, such as anthracite or dry steam coal or coke breeze, e. g. in the proportions of 30%-10% of binding medium to %-90% of the base material or materials, pressing or moulding this mixture into briquettes, removing the latter from the press or moulds, and then subjecting the briquettes after removal from the press or moulds to heat treatment for the purposes described.

2. A process for the manufacture of fuel briquettes which consists in forming a binding medium from caking coal reduced to an impalpable powder or a finely comminuted state such as to pass 150-200 (or finer) mesh, mixed with only enough liquid such for example as water or/and tar or other suitable liquid hydrocarbons to thereby form a smooth homogeneous paste, mixing a suit able proportion of this binding medium with a base material or materials of a non caking character, such as anthracite or dry steam coal or coke breeze, e. g. in the proportions of 30%-10% of binding medium to 7070-9070 of the base material or mate rials, pressing or moulding this mixture into briquettes, removing the latter from the press or moulds, and then subjecting the briquettes after removal from the press or. moulds to a heat treatment such that the finished briquettes are rendered hard, dense, and substantially non-porous, and contain 5% or thereabouts of volatile matter.

8. A process for the manufacture of fuel briquettes which consists in forming a binding medium from caking coal reduced to an impalpable powder or a finely comminuted state such as to pass 150-200 (or finer) mesh, mixed with only enough liquid such for example as water or/and tar or other suitable liquid hydrocarbons to thereby form a smooth homogeneous paste, mixing a suitable proportion of this binding medium with a base material or materials of a non caking character, such as anthracite or dry steam coal or coke breeze, e. g. in the proportions of 30%10% of binding medium to 70%-90% of the base material or materials, pressing or moulding this mixture into briquettes, removing the latter from the press or moulds, and then subjecting the briquettes after removal from the press to a heat treatment in which the temperatures to which the briquettes are subjected during such heat treatment after moulding range from 600 to 1200 F.

4:. A process for the manufacture of fuel briquettes which consists in forming a binding medium from caking coal reduced to an impalpable powder or a finely comminuted state such as to pass 150-200 (or finer) mesh mixed with only enough liquid such for example as water or/and tar or other suitable liquid hydrocarbons to thereby form a smooth homogeneous paste, mixing a suitable proportion of this'binding medium with a base material or materials of a non-caking character, such as anthracite or dry steam coal or coke breeze, e. g. in the proportions of 30%-10% of binding medium to 70%- of the base material or materials, the combined volatile content of the combined non-caking coal and (taking coal being in the region of 7% to 11% of the mass, pressing or moulding this mixture into briquettes, and submitting the said briquettesa;tter removal from the press or mould-to partial distillation or baking advantageously at a temperature of from 600 to 1200 F. to drive off a proportion of the volatiles and consolidate the briquettes.

THOMAS AUGUSTUS GOSKAR. 

